Spinal artificial disc removal tool

ABSTRACT

An extraction tool for removing an installed artificial disc from a spine is provided. The extraction tool is impacted between the artificial disc and the vertebrae and engages the artificial disc to allow a surgeon to remove the artificial disc from the spine.

PRIORITY

The present application is a divisional application of U.S. applicationSer. No. 17/028,888, filed Sep. 22, 2020, which is herein incorporatedby reference in its entirety, and which claims the benefit of U.S.Provisional Application Ser. No. 62/904,680, filed Sep. 23, 2019, whichis herein incorporated by reference in its entirety.

THE FIELD OF THE INVENTION

The present invention relates to artificial spinal discs. In particular,examples of the present invention relate to a tool for removing aninstalled artificial spinal disc.

BACKGROUND

Various companies have developed artificial discs to replace damagedspinal discs. These artificial discs preserve mobility in the spine andare frequently preferable to fusion of the vertebrae. In some instances,it becomes necessary to remove an artificial disc. This may occur duringsurgery or after installation of an artificial disc.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive examples of the present invention aredescribed with reference to the following figures, wherein likereference numerals refer to like parts throughout the various viewsunless otherwise specified.

FIG. 1 is a drawing of an artificial spinal disc.

FIG. 2 is a drawing of an artificial spinal disc.

FIG. 3 is a drawing of an artificial disc installed in a spine.

FIG. 4 is a drawing showing a side view of an artificial disc extractiontool for removing an installed artificial disc from a spine.

FIG. 5 is a drawing showing an exploded side view of the artificial discextraction tool.

FIG. 6 is a drawing showing an exploded perspective view of theartificial disc extraction tool.

FIG. 7 is a perspective drawing of the artificial disc extraction tooltines.

FIG. 8 is a drawing of the artificial disc extraction tool tines.

FIG. 9 is a drawing showing the use of the artificial disc extractiontool.

FIG. 10 is a drawing showing the use of the artificial disc extractiontool.

FIG. 11 is a drawing showing the use of the artificial disc extractiontool.

FIG. 12 is a drawing showing the use of the artificial disc extractiontool.

FIG. 13 is a drawing showing the use of the artificial disc extractiontool.

FIG. 14 is a drawing showing the use of the artificial disc extractiontool.

FIG. 15 is a drawing showing a top view of an artificial disc extractiontool.

FIG. 16 is a drawing showing a top view of the artificial discextraction tool of FIG. 15 .

FIG. 17 is a drawing showing a side view of the artificial discextraction tool of FIG. 15 .

FIG. 18 is a drawing showing a top view of an artificial disc extractiontool.

FIG. 19 is a drawing showing a top view of the artificial discextraction tool of FIG. 18 .

FIG. 20 is a drawing showing a side view of the artificial discextraction tool of FIG. 18 .

FIG. 21 is a drawing showing a top view of an artificial disc extractiontool.

FIG. 22 is a drawing showing a top view of an artificial disc extractiontool.

FIG. 23 is a drawing showing a side view of an artificial discextraction tool.

FIG. 24 is a drawing showing a side view of the artificial discextraction tool of FIG. 23 .

FIG. 25 is a drawing showing a top view of the artificial discextraction tool of FIG. 23 .

FIG. 26 is a drawing showing a top view of the artificial discextraction tool of FIG. 23 .

FIG. 27 is a drawing showing a side view of an artificial discextraction tool.

FIG. 28 is a drawing showing a top view of the artificial discextraction tool of FIG. 27 .

FIG. 29 is a drawing showing a top view of the artificial discextraction tool of FIG. 27 .

FIG. 30 is a drawing showing a top view of the artificial discextraction tool of FIGS. 23 and 27 .

FIG. 31 is a drawing showing a side view of an artificial discextraction tool.

FIG. 32 is a drawing showing a top view of the tines of an artificialdisc extraction tool.

Corresponding reference characters indicate corresponding componentsthroughout the several views of the drawings. Unless otherwise noted,the drawings have been drawn to scale. Skilled artisans will appreciatethat elements in the figures are illustrated for simplicity and clarity.For example, the dimensions of some of the elements in the figures maybe exaggerated relative to other elements to help improve understandingof various examples of the present invention. Also, common butwell-understood elements that are useful or necessary in a commerciallyfeasible embodiment are often not depicted in order to facilitate a lessobstructed view of these various embodiments of the present invention.

It will be appreciated that the drawings are illustrative and notlimiting of the scope of the invention which is defined by the appendedclaims. The examples shown each accomplish various different advantages.It is appreciated that it is not possible to clearly show each elementor advantage in a single figure, and as such, multiple figures arepresented to separately illustrate the various details of the examplesin greater clarity. Similarly, not every example need accomplish alladvantages of the present disclosure.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the present invention. Itwill be apparent, however, to one having ordinary skill in the art thatthe specific detail need not be employed to practice the presentinvention. In other instances, well-known materials or methods have notbeen described in detail in order to avoid obscuring the presentinvention.

In the above disclosure, reference has been made to the accompanyingdrawings, which form a part hereof, and in which are shown by way ofillustration specific implementations in which the disclosure may bepracticed. It is understood that other implementations may be utilizedand structural changes may be made without departing from the scope ofthe present disclosure. References in the specification to “oneembodiment,” “an embodiment,” “an example embodiment,” etc., indicatethat the embodiment described may include a particular feature,structure, or characteristic, but every embodiment may not necessarilyinclude the particular feature, structure, or characteristic. Moreover,such phrases are not necessarily referring to the same embodiment.Further, when a particular feature, structure, or characteristic isdescribed in connection with an embodiment, such feature, structure, orcharacteristic may be used in connection with other embodiments whetheror not explicitly described. The particular features, structures orcharacteristics may be combined in any suitable combination and/orsub-combinations in one or more embodiments or examples. It isappreciated that the figures provided herewith are for explanationpurposes to persons ordinarily skilled in the art.

As used herein, “adjacent” refers to near or close sufficient to achievea desired effect. Although direct contact is common, adjacent canbroadly allow for spaced apart features.

As used herein, the singular forms “a,” and, “the” include pluralreferents unless the context clearly dictates otherwise.

As used herein, the term “substantially” refers to the complete ornearly complete extent or degree of an action, characteristic, property,state, structure, item, or result. For example, an object that is“substantially” enclosed would mean that the object is either completelyenclosed or nearly completely enclosed. The exact allowable degree ofdeviation from absolute completeness may in some cases depend on thespecific context. However, generally speaking the nearness of completionwill be so as to have the same overall result as if absolute and totalcompletion were obtained. The use of “substantially” is equallyapplicable when used in a negative connotation to refer to the completeor near complete lack of an action, characteristic, property, state,structure, item, or result. For example, a composition that is“substantially free of” particles would either completely lackparticles, or so nearly completely lack particles that the effect wouldbe the same as if it completely lacked particles. In other words, acomposition that is “substantially free of” an ingredient or element maystill actually contain such item as long as there is no measurableeffect thereof.

As used herein, the term “about” is used to provide flexibility to anumber or numerical range endpoint by providing that a given value maybe “a little above” or “a little below” the number or endpoint.

As used herein, a plurality of items, structural elements, compositionalelements, and/or materials may be presented in a common list forconvenience. However, these lists should be construed as though eachmember of the list is individually identified as a separate and uniquemember. Thus, no individual member of such list should be construed as ade facto equivalent of any other member of the same list solely based ontheir presentation in a common group without indications to thecontrary.

Dimensions, amounts, and other numerical data may be expressed orpresented herein in a range format. It is to be understood that such arange format is used merely for convenience and brevity and thus shouldbe interpreted flexibly to include not only the numerical valuesexplicitly recited as the limits of the range, but also to include allthe individual numerical values or sub-ranges encompassed within thatrange as if each numerical value and sub-range is explicitly recited. Asan illustration, a numerical range of “about 1 to about 5” should beinterpreted to include not only the explicitly recited values of about 1to about 5, but also include individual values and sub-ranges within theindicated range. Thus, included in this numerical range are individualvalues such as 2, 3, and 4 and sub-ranges such as from 1-3, from 2-4,and from 3-5, etc., as well as 1, 2, 3, 4, and 5, individually.

Artificial spinal discs may be installed surgically to replace a damagedspinal disc. Generally, a damaged spinal disc may be treated by fusingthe adjacent vertebrae together or by replacing the disc with anartificial disc. As more sophisticated spinal discs are developed byvarious medical device companies, replacement of a damaged disc with anartificial disc is increasingly preferable to fusion of adjacentvertebrae as it preserves a degree of motion at that location within thespine. Surgeries to install artificial discs have a degree ofunpredictability which may not be observed from pre-operativeexamination. Variable condition of the bone and surgical site, forexample, may be observed by the surgeon. In some situations, it hasbecome necessary to remove an installed artificial spinal disc from apatient. This may occur during the original surgical procedure toinstall the artificial spinal disc. For example, continued bleeding fromthe bone surfaces of the vertebrae may require removal of an installedartificial disc. The surgeon may then perform additional treatmentprocedures and reinstall the artificial disc.

Turning now to FIG. 1 , a perspective view of an artificial (prosthetic)disc 10 used to replace a damaged spinal disc is shown. The artificialdisc 10 includes an articular body 14 which includes components thatinteract with each other to provide articulating motion to theartificial disc. The articular body 14 may include an upper and a lowerarticulation surface, an elastomeric articulation component, etc.Companies have created artificial discs with different types ofarticular bodies 14 including a ball in socket joint, a ball in troughjoint, elastomeric joints, and complex articulation surfaces. Thearticular body 14 as described is often formed by part of the upperportion 18 of the artificial disc 10 and part of the lower portion 22 ofthe artificial disc. 10. The articular body 14 may also include anadditional component located between the upper portion 18 and lowerportion 22 of the artificial disc 10 such as an elastomeric component ora core.

The upper portion 18, or upper plate, of the artificial disc 10typically attaches to or includes part of the articular body 14 andincludes an upper bone attachment surface 26. The upper bone attachmentsurface 26 often includes one or two keels 30 to aid in fixation of theupper portion 18 and an adjacent vertebra. The upper keels 30 extendupwardly from the upper portion 18 of the artificial disc 10. The boneattachment surface 26 may be treated to provide initial mechanical gripfor initial bone fixation and also allows for bone ingrowth(osseointegration) for long term fixation of the artificial disc 10. Thebone attachment surface 26 may be roughened or include a rough titaniumplasma coating, bead coating, or particulate coating that provides themechanical grip and allows for bone ingrowth. The lower portion 22, orlower plate, of the artificial disc 10 typically attaches to or includespart of the articular body 14 and a lower bone attachment surface 34.The lower bone attachment surface also includes one or two keels 30 toaid in fixation of the lower portion 22 to an adjacent vertebra. Thelower keels 30 extend downwardly from the lower portion 22 of theartificial disc 10. The bone attachment surface 34 may be treated toprovide mechanical grip and to allow for bone ingrowth. The boneattachment surface 34 may be roughened or include a rough titaniumplasma coating, bead coating, or particulate coating that provides themechanical grip and allows for bone ingrowth.

For an artificial disc 10 such as a ball in socket joint or a joint witha complex articular surface, the upper portion 18 may be an upper platewhich is configured to attach to a vertebra above the installedartificial disc 10. The upper portion 18 may include an upper attachmentsurface 26 with an upper keel 30. The upper part of the articular body14, such as a ball or complex articulation surface, may be formed aspart of the upper portion 18. The lower portion 22 may be a lower platewhich is configured to attach to a vertebra below the installedartificial disc 10. The lower portion 22 may include a lower attachmentsurface 34 with a lower keel 30. The lower part of the articular body14, such as a socket or trough or a complex articulation surface, may beformed as part of the lower portion 22. The upper portion 18 and lowerportion 22 may contact each other and provide articulation motiontherebetween in an installed disc 10 to provide the desired motion tothe patient. FIG. 1 shows an artificial disc 10 with two keels 30 oneach bone attachment surface 26, 34. FIG. 2 shows a similar artificialdisc 10 which differs in that it includes a single keel 30 on each boneattachment surface 26, 34.

FIG. 3 shows a lateral view of an installed artificial spinal disc 10.The artificial disc 10 is installed between two vertebrae 38 to replacea natural spinal disc (e.g. 42) which is damaged. For an examplecervical disc, an anterior incision is made in the neck and ligamentsand muscles are retracted to expose the damaged spinal disc. The damagednatural disc and cartilage are removed and disc height is restored.Slots are created in the vertebrae 38 to receive the keels 30 of theartificial discs 10. The artificial disc 10 is installed between theprepared vertebrae 38; placing the keel 30 into the slots in thevertebrae 38. The keels 30 and surface of the bone attachment surfaces26, 34 provide short term fixation of the artificial spinal disc 10 andsecure the artificial disc 10 to the vertebrae 38.

In some cases, it becomes necessary to remove the artificial disc 10after installation. There may be continued bleeding from the vertebrae,for example, which necessitates removal of the artificial disc 10 andcorrection before finishing the disc replacement surgery. FIGS. 4through 6 show an artificial spinal disc extraction tool 46. FIG. 4shows a side view of the extraction tool 46. FIG. 5 shows an explodedside view of the extraction tool 46. FIG. 6 shows an explodedperspective view of the extraction tool 46.

The extraction tool 46 includes an upper extraction tool member 50 and alower extraction tool member 52 which are separable from each other. Theupper extraction tool member 50 and the lower extraction tool member 52are attachable together during use and an artificial disc 10 istypically extracted after the extraction tool 46 is attached together inthe configuration shown in FIG. 4 . The upper extraction tool member 50and the lower extraction tool member 52 each includes a body 54, arms 58which extend distally from the body 54, and tines 62 disposed at thedistal end of the arms 58. Each extraction tool member 50, 52 includestwo arms 58 which extend distally from the body 54 and each arm 58includes a tine 62 on its end so that each extraction tool memberincludes two tines 62. For each extraction tool member 50, 52, the arms58 may pivot or flex away from each other or towards each other toengage or disengage the artificial disc keels 30.

Each extraction tool member 50, 52 includes an actuator, such asexpansion pin 66 with a tapered distal end 70 and a threaded section 74typically disposed on the proximal end of the expansion pin 66. Theexpansion pin 66 is located in a channel or bore formed through theextraction tool member 50, 52. The threaded section 74 of each expansionpin 66 engages a correspondingly threaded receiver 78 on the extractiontool member 50, 52. In the example extraction tool 46, the threadedsections 74 and threaded receivers 78 are disposed at the proximal endsof the expansion pins 66 and the bodies 54 of each extraction toolmember 50, 52. The proximal ends of the expansion pins 66 include adrive socket 82 such as a hex socket or Torx socket. This allows a userto turn the expansion pins 66 with a drive tool to advance or retractthe expansion pins 66 within the extraction tool member 50, 52.

As is visible in FIG. 6 , each extraction tool member 50, 52 includes aslot 86 which extends lengthwise through approximately the distal halfof the extraction tool member and separates the two arms 58 and tines62. The slot 86 allows the arms 58 and tines 62 to flex and move towardsor away from each other. Generally, the slot 86 extends through thetines 62 and arms 58 and does not extend through the body section 54.The expansion pins 66 extend through a channel 90 through the actuatortool member 50, 52. The distal end of each arm 58 includes an angledramp 94 such that each extraction tool member 50, 52 includes a pair ofangled ramps 94. The angled ramps 94 are disposed opposite each otherand are disposed on the distal ends of the arms 58 hear the tines 62.The faces of the angled ramps 94 define an included angle therebetweenwhich is approximately equal to the angle of the tapered distal ends 70of the expansion pins 66. When the expansion pins 66 are placed withineach extraction tool member 50, 52, the threaded section 74 of theexpansion pin engages the threaded receiver 78 of the body 54 and thetapered distal ends 70 are disposed adjacent the angled ramps 94. Usinga drive tool to rotate the expansion pins 66 clockwise advances theexpansion pins 66 distally within the extraction tool member 50, 52 andforces the tapered distal end 70 to advance between the angled ramps 94;spreading the arms 58 and tines 62 apart from each other. Using thedrive tool to rotate the expansion pins 66 counter-clockwise retractsthe expansion pins 66 and moves the tapered ends 70 proximally away fromthe angled ramps 94; allowing the tines 62 to move towards each other.

FIG. 7 shows a more detailed perspective view of a pair of tines 62 onone extraction tool member 50, 52. FIG. 8 shows a more detailed top viewof the pair of tines 62. Each tine 62 includes a thin tine body 98 witha tip 102. The tine body 98 is made thin as it is driven between theinstalled artificial disc 10 and the vertebra 38 during use. One outsideface of the tip 102 of each tine 62 is beveled and tapers such that thedistal end of the tine body 98 is thinner than the proximal tine body98. As is visible in FIG. 4 , the tine 62 is flat on the side whichfaces the artificial disc 10 and the tapered face of the tip 102 islocated on the side of the tine body 98 which faces away from theartificial disc 10 in use. The tip 102 is shaped so that the flat innerside slides along the bone attachment surface 26, 34 of the artificialdisc 10 and the tapered face of the tip 102 slides along the preparedsurface of the vertebra 38; minimizing damage to the bone and wedgingbetween the bone 38 and the artificial disc 10 to dislodge the keels 30from the bone. Each tip 102 includes a keel tab 106 which is angledrelative to the tine body 98 and which extends laterally away from thetine body 98. Each keel tab 106 forms a small angular notch on the sideof each tine 62. The tine body 98 is spaced apart from the middle of theartificial disc extraction tool 46 by a distance indicated generally at108 which is approximately equal to half of the thickness of theartificial disc 10. This creates a space 112 (FIG. 4 ) between tines 62in the assembled extraction tool 46 which receives an artificial disc10.

In use, the surgeon will typically start with each extraction toolmember 50, 52 separated from each other and with the expansion pins 66retracted so that the arms 58 and tines 62 are positioned towards eachother as shown in FIG. 7 . One extraction tool member 50, 52 (such asthe upper member 50) is driven between the installed artificial disc 10(e.g. the top) and the adjacent vertebra 38 as is shown in FIG. 9 . Theextraction tool member 50 is moved into this position by moving thetines 62 between the keels 30 of the artificial disc 10 until the keeltabs 106 are past the keels 30. A driver tool 110 is used to advance theexpansion pin 66 and move the tines 62 apart from each other by wedgingthe tapered distal end 70 of the pin 66 between the angled ramps 94.This moves the tine keel tabs 106 apart laterally and moves them pastthe keels 30. If desired, the expansion pin 66 may be advanced until thetine bodies 98 are pressed against the inside edges of the keels 30 tostabilize the extraction tool member 50.

The second extraction tool member 52 is then driven between the otherside (e.g. the bottom) of the installed artificial disc 10 and theadjacent vertebra 38. The extraction tool member 52 is moved into thisposition by moving the tines 62 between the keels 30 of the artificialdisc 10 until the keel tabs 106 are past the keels 30. The twoextraction tool halves 50, 52 are then attached to each other, such asby engaging a tab 114 (FIG. 6 ) on one extraction tool member 52 with acorresponding slot on the other extraction tool member 50. The drivertool 110 is used to advance the expansion pin 66 and move the tines 62apart from each other by wedging the tapered distal end 70 of the pin 66between the angled ramps 94. This moves the tine keel tabs 106 apartlaterally and moves them past the keels 30. If desired, the expansionpin 66 may be advanced until the tine bodies 98 are pressed against theinside edges of the keels 30 to stabilize the extraction tool member 50.The artificial spinal disc extraction tool 46 is now in theconfiguration shown in FIG. 10 . The extraction tool 46 mayalternatively be attached to an installed artificial spinal disc 10 bydriving the first extraction tool member 50 between the artificial disc10 and a vertebra 38, driving the second extraction tool member 52between the artificial disc and a vertebra 38, connecting the extractiontool halves 50, 52 together, and then expanding the tines 62 to engagethe keels 30. FIG. 11 shows a perspective view of the extraction tool 46without expanding the tines 62 to illustrate how the tines 62 fitbetween the keels 30 of an artificial disc 10.

FIG. 12 shows a drawing of the tines 62 and artificial disc 10. Thetines 62 are shown how they would be positioned after driving thembetween the artificial disc 10 and a vertebra 38 and before the tines 62have been expended. FIG. 13 shows the extraction tool tines 62 after theexpansion pin 66 has been advanced forwards to expand the tines 62. Thetapered distal end 70 of the expansion pin 66 has been forced betweenthe angled ramps 94; moving the tines 62 apart to engage the keels 30.

Once the tines 62 of both extraction tool halves 50, 52 are expandedagainst the keels 30 as shown in FIG. 13 , a handle or slap hammer 118may be attached to the extraction tool 46 as is shown in FIG. 14 . Theslap hammer 118 has a keyway slot 122 formed in one end of the slaphammer 118. The keyway slot 122 is attached to shoulders 126 and arecess 130 (FIGS. 4-6 ) formed at the proximal ends of the body 54 ofeach extraction tool member 50, 52. The slap hammer 118 may be used topull the artificial disc 10 from between the vertebrae 38. The keel tabs106 formed on the tines 62 engage the keels 30 and pull the artificialdisc from the vertebrae 38. Both the upper portion 18 and the lowerportion 22 of the artificial disc 10 are removed simultaneously from thespine. The extraction tool 46 may then be disassembled to release theartificial disc 10.

FIG. 15 through 17 show an extraction tool 46 configured to extract anartificial disc 10 with a single keel 30 on each of the top and bottomof the artificial disc 10. FIG. 15 shows a top view of the extractiontool 46 with the tines 62 expanded in an insertion position. FIG. 16shows a top view of the extraction tool 46 with the tines 62 movedinwardly in a closed position where they capture the keels 30. FIG. 17shows a side view of the extraction tool 46. The extraction tool 46functions as discussed above except as otherwise noted. The extractiontool 46 includes a body 54, two upper arms 58 which extend distally fromthe body 54, and two tines 62 disposed at the distal end of the arms 58.The extraction tool 46 also includes two lower arms 58 with two tines 62disposed at the distal ends of the lower arms. The upper tines 62 areinserted above the artificial disc 10 and the lower tines 62 areinserted beneath the artificial disc 10 during use as shown in FIG. 14 .

Each tine 62 includes a thin tine body 98 with a tip 102. The tine body98 is made thin as it is driven between the installed artificial disc 10and the vertebra 38 during use. One outside face of the tip 102 of eachtine 62 is beveled and tapers such that the distal end of the tine body98 is thinner than the proximal tine body 98. As is visible in FIG. 4 ,the tine 62 is flat on the side which faces the artificial disc 10 andthe tapered face of the tip 102 is located on the side of the tine body98 which faces away from the artificial disc 10 in use. The tip 102 isshaped so that the flat inner side slides along the bone attachmentsurface 26, 34 of the artificial disc 10 and the tapered face of the tip102 slides along the prepared surface of the vertebra 38; minimizingdamage to the bone and wedging between the bone 38 and the artificialdisc 10 to dislodge the keels 30 from the bone. Each tip 102 includes akeel tab 106 which is angled relative to the tine body 98 and whichextends laterally inwardly from the tine body 98. Each keel tab 106forms a small angular notch on the inside of each tine 62. The tine body98 is sufficiently long to capture the artificial disc 10 in a space 112(FIGS. 4, 17 ) between tines 62 in the assembled extraction tool 46receives an artificial disc 10.

The upper arms 58 and lower arms 58 are angled slightly apart from eachother in the open, insertion configuration. The upper arms 58 and lowerarms 58 flex or pivot towards each other into a closed configurationwhich allows the extraction tool 46 to engage and capture the artificialdisc keels 30. An actuator, collar 134, is disposed around the body 54of the extraction tool 46. Parts of the extraction tool 46 which arecovered by the collar 134 are shown to facilitate understanding of thestructure. The collar 134 is internally threaded (indicated in dashedlines at 138) and threads 142 are formed on the body 54 of theextraction tool 46. The collar 134 may be rotated relative to the body54 to advance the collar 134 distally or retract the collar proximallyrelative to the body 54. When the collar 134 is advanced distally, thedistal end of the collar 134 engages the arms 58 and presses in the arms58 inwardly towards each other. This moves the keel tabs 106 towardseach other and captures the keel 30 between the tines 62 and keel tabs106 as is shown in FIG. 16 . The actuator, collar 134, may also functionas a clamp which presses the upper arms 58 towards the lower arms 58 tothereby press the tines 62 against the artificial disc 10.

FIG. 17 shows a side view of the extraction tool 46. The extraction tool46 may include an upper member 50 and a lower member 52 which may beinserted separately between the artificial disc 10 and vertebra 38.

In use, the tines 62 of the extraction tool 46 are driven between theartificial disc 10 and the vertebrae 38 to separate the artificial discfrom the vertebrae 38. The collar 134 is then rotated and advanceddistally along the body 54 to move the arms 58 and tines 62 towards eachother and capture the artificial disc keels 30 between the tines 62 andkeel tabs 106. A slap hammer 118 may be attached to the extraction tool46 if desired and the extraction tool may be moved proximally away fromthe spine to remove the artificial disc 10 from between the vertebrae38. The collar 134 may then be rotated and retracted proximally alongthe body 54 to release the artificial disc 10. The extraction tool 46may include first indicator marks 146 which show how far to insert tothe extraction tool 46 relative to the artificial disc 10 and secondindicator marks 150 which show how far to advance the actuator/collar134 to move the arms 58 inwardly and capture the keel 30 with the tines62 and keel tabs 106. The extraction tool 46 may include shoulders 154disposed between the tines 62 and arms 58 which provide a reference forinsertion of the extraction tool 46 between the artificial disc 10 andvertebrae 38 and which may contact the artificial disc 10 at fullinsertion.

FIG. 18 through 20 show an extraction tool 46 configured to extract anartificial disc 10 with a single keel 30 on each of the top and bottomof the artificial disc 10. FIG. 18 shows a top view of the extractiontool 46 with the tines 62 expanded in an insertion position. FIG. 19shows a top view of the extraction tool 46 with the tines 62 movedinwardly in a closed position where they capture the keels 30. FIG. 20shows a side view of the extraction tool 46. The extraction tool 46functions as discussed above and particularly in the same manner as inFIGS. 15 through 17 except that the extraction tool 46 includes a collar134 which is positioned along the extraction tool 46 with a threadedactuator rod 158. The actuator rod 158 may have a distal end which isattached to the collar 134 and which rotates relative to the collar 134.The proximal portion of the actuator rod 158 includes threads andengages a threaded boss 162 on the extraction tool body 54. The proximalend of the actuator rod 158 includes a drive socket (such as a Torxsocket) and receives a drive tool to rotate the actuator rod 158 andadvance or retract the collar distally or proximally along theextraction tool body 54. FIG. 20 shows how the upper member 50 of theextraction tool and the lower member 52 of the extraction tool 46 mayeach have a separate collar 134, actuator rod 158, and threaded boss162. This allows each member of the extraction tool 46 to be insertedand locked around the artificial disc keel 30 separately. FIG. 20 alsoshows how a fixed or adjustable depth stop 156 may be attached to an arm58 of each extraction tool member. The depth stop 156 may contact thebone 38 or artificial disc 10 at full insertion of the extraction tool46.

FIG. 21 shows a top view of an extraction tool 46. The extraction tool46 operates similarly to pliers and is configured to extract anartificial disc 10 with a single keel 30 on top and on bottom of theartificial disc 10. The extraction tool 46 includes upper arms 58 andlower arms 58 which are attached together at a pivot point 166 andextend distally from the extraction tool body 54. Tines 62 are disposedon the distal ends of the arms. Each tine 62 includes a thin tine body98 with a tip 102. The tine body 98 is made thin as it is driven betweenthe installed artificial disc 10 and the vertebra 38 during use. Oneoutside face of the tip 102 of each tine 62 is beveled and tapers suchthat the distal end of the tine body 98 is thinner than the proximaltine body 98. As is visible in FIG. 4 , the tine 62 is flat on the sidewhich faces the artificial disc 10 and the tapered face of the tip 102is located on the side of the tine body 98 which faces away from theartificial disc 10 in use. The tip 102 is shaped so that the flat innerside slides along the bone attachment surface 26, 34 of the artificialdisc 10 and the tapered face of the tip 102 slides along the preparedsurface of the vertebra 38; minimizing damage to the bone and wedgingbetween the bone 38 and the artificial disc 10 to dislodge the keels 30from the bone. Each tip 102 includes a keel tab 106 which is angledrelative to the tine body 98 and which extends laterally inwardly fromthe tine body 98. Each keel tab 106 forms a small angular notch on theinside of each tine 62. The tine body 98 is sufficiently long to capturethe artificial disc 10 in a space 112 (FIG. 4 ) between tines 62 in theassembled extraction tool 46 receives an artificial disc 10.

The body 54 of the extraction tool 46 includes two handles 170, 174.Each handle 170, 174 may be attached to an upper arm 58 and a lower arm58. The handles 170, 174 may be pivoted towards each other after thetines 62 are inserted between the artificial disc 10 and the vertebraeto pivot the tines 62 towards each other and capture the keel 30 andthen extract the artificial disc 10. A latch mechanism such as a lockingstrap 178 may be pivotably attached to one handle 170 and includenotches 182, 186 to engage the other handle 174 and alternately hold thehandles in an open, insertion position or a closed, extraction position.One handle 170 may include a shoulder 126 and recess 130 to allowattachment of a slap handle 118.

FIG. 22 shows a top view of an extraction tool 46. The extraction tool46 operates similarly to pliers and is configured to extract anartificial disc 10 with two keels 30 on top and two keels 30 on bottomof the artificial disc 10. The extraction tool 46 includes upper arms 58and lower arms 58 which are attached together at a pivot point 166 andextend distally from the extraction tool body 54. Tines 62 are disposedon the distal ends of the arms. Each tine 62 includes a thin tine body98 with a tip 102. The tine body 98 is made thin as it is driven betweenthe installed artificial disc 10 and the vertebra 38 during use. Oneoutside face of the tip 102 of each tine 62 is beveled and tapers suchthat the distal end of the tine body 98 is thinner than the proximaltine body 98. As is visible in FIG. 4 , the tine 62 is flat on the sidewhich faces the artificial disc 10 and the tapered face of the tip 102is located on the side of the tine body 98 which faces away from theartificial disc 10 in use. The tip 102 is shaped so that the flat innerside slides along the bone attachment surface 26, 34 of the artificialdisc 10 and the tapered face of the tip 102 slides along the preparedsurface of the vertebra 38; minimizing damage to the bone and wedgingbetween the bone 38 and the artificial disc 10 to dislodge the keels 30from the bone. Each tip 102 includes a keel tab 106 which is angledrelative to the tine body 98 and which extends laterally inwardly fromthe tine body 98. Each keel tab 106 forms a small angular notch on theinside of each tine 62. The tine body 98 is sufficiently long to capturethe artificial disc 10 in a space 112 (FIG. 4 ) between tines 62 in theassembled extraction tool 46 receives an artificial disc 10.

The body 54 of the extraction tool 46 includes two handles 170, 174.Each handle 170, 174 may be attached to an upper arm 58 and a lower arm58. The handles 170, 174 may be pivoted towards each other after thetines 62 are inserted between the artificial disc 10 and the vertebraeto pivot the tines 62 away from each other and capture the keels 30 withthe keel tabs 106 and then extract the artificial disc 10. A latchmechanism such as a locking strap 178 may be pivotably attached to onehandle 170 and include notches 182, 186 to engage the other handle 174and alternately hold the handles in an open, insertion position or aclosed, extraction position. One or both handles 170, 174 may include ashoulder 126 and recess 130 to allow attachment of a slap handle 118.

With the plier embodiments of the extraction tools 46 shown in FIGS. 21and 22 , a single extraction tool 46 may include upper arms 58 and lowerarms 58 and engage both the top and bottom of the artificial disc 10.Alternatively, a separate extraction tool upper member 50 and lowermember 52 may be provided with the shape shown in FIGS. 21 and 22 . Theextraction tool halves 50, 52 may be inserted separately around theartificial disc 10 and the artificial disc may then be removed.

FIGS. 23 through 26 show an extraction tool 46 configured to extract anartificial disc 10 with two keels 30 on each on the upper boneattachment surface 26 and two keels on the lower attachment surface 34of the artificial disc 10. FIGS. 23 and 24 show side views of theextraction tool 46. FIG. 25 shows a top view of the extraction tool 46.The extraction tool 46 functions as discussed above except as otherwisenoted. The extraction tool 46 includes an upper member 50 with a body54, an upper arm 58 which extends distally from the body 54, and a tine62 disposed at the distal end of the arm 58. The extraction tool 46 alsoincludes a lower member 52 with a lower arm 58 which extends distallyfrom the body 54, and a tine 62 disposed at the distal ends of the lowerarm 58. The upper member 50 of the extraction tool and the lower portionof the extraction tool are separate; allowing the upper member 50 andlower member 52 to be inserted between an artificial disc 10 and theadjacent vertebrae independently. The upper tines 62 are inserted abovethe artificial disc 10 and the lower tines 62 are inserted beneath theartificial disc 10 during use as shown in FIG. 14 .

Each tine 62 includes a thin tine body 98 with a tip 102. The tine body98 is made thin as it is driven between the installed artificial disc 10and the vertebra 38 during use. One outside face of the tip 102 of eachtine 62 is beveled and tapers such that the distal end of the tine body98 is thinner than the proximal tine body 98. The tine 62 is flat on theside which faces the artificial disc 10 and the tapered face of the tip102 is located on the side of the tine body 98 which faces away from theartificial disc 10 in use and contacts the vertebra 38. The tine 62 isshaped so that the flat inner side slides along the bone attachmentsurface 26, 34 of the artificial disc 10 and the tapered face of the tip102 slides along the prepared surface of the vertebra 38; minimizingdamage to the bone and wedging between the bone 38 and the artificialdisc 10 to dislodge the keels 30 from the bone. The tine body 98 issufficiently long to capture the artificial disc 10 in a space 112between tines 62 in the assembled extraction tool 46 as the extractiontool receives an artificial disc 10.

The proximal end of the extraction tool 46 includes shoulders 126 and arecess 130 located distally from the shoulders 126. A slap handle 118may be attached to the shoulders 126 and used to extract the artificialdisc 10 if desired. The distal end of the extraction tool may be roundedto allow it to me more easily driven between the artificial disc 10 anda vertebra 38.

FIG. 24 shows the extraction tool fully inserted around an installedartificial disc 10. The tines 62 extend along the anterior/posteriorlength of the artificial disc 10 and both the upper member 50 and thelower member 52 of the extraction tool 46 have been inserted to an equaldepth relative to the artificial disc 10. A clamp, collar 134, may beplaced around the extraction tool body 54 and used to clamp the tines 62against the artificial disc 10. The collar 134 may be a C-shaped collarwhich has an opening along its length and which allows it to be placedover the proximal end of the extraction tool body 54. Alternatively, thecollar 134 may be larger in diameter than the proximal end of theextraction tool 46 (e.g. the shoulders 126) and the collar 134 may beplaced over the proximal end of the extraction tool 46 and over the toolbody 54. The extraction tool body 54 tapers and becomes larger towardsthe distal end such that the proximal end of the extraction tool body 54is smaller and the distal end of the extraction tool body 54 is larger.Moving the collar 134 towards the distal end of the extraction tool 46will cause the collar 134 to engage the extraction tool body 54 andpress the upper member 50 and lower member 52 of the extraction tool 46against each other. This will secure the artificial disc 10 between thetines 62. The extraction tool body 54 and the interior of the collar 134may be threaded and these engaging threads may be used to advance thecollar distally along the tool body 54.

The net distance 112 between the tines 62 is slightly less than thethickness of the artificial disc 10 so that a small space 194 is leftbetween the upper member 50 and lower member 52 of the extraction tool46. This space 194 allows the collar 134 to press the tines 62 againstthe artificial disc 10.

FIG. 25 shows a top view of the extraction tool 46 and the artificialdisc 10. In the example embodiment, the tines 62 do not have keel tabs106 and may simply slide between the keels 30. The tines 62 may be madewider than the spacing between the keels 30 and one or more slots may beformed in the tines 62 which each allow a keel 30 to enter into a slotas the tines 62 are inserted around the artificial disc 10. This mayallow a similarly designed extraction tool to function with anartificial disc 10 with a single keel 30 or with other numbers of keels30.

In many instances, there is little resistance to removing the artificialdisc 10 once the tines 62 have been inserted between the bone attachmentsurfaces 26, 34 and the vertebrae 38. In these situations, theartificial disc 10 may be removed with just the frictional grip betweenthe tines 62 and the bone attachment surfaces 26, 34.

The extraction tool 46 may alternatively have small keel tabs 106 whichare spring loaded and extend from the tines 62 once the tines 62 areinserted past the keels. The tines 62 may also have longitudinal slots198 therethrough with increase their lateral flexibility and small keeltabs 106 as shown in FIG. 26 . The slots 198 create smaller fingers inthe tines 62 which flex inwardly during insertion and allow the keeltabs 106 to pass between the keels 30 and then spring back outwardlyonce the tine 62 is fully inserted along the artificial disc 10.

FIGS. 27 through 29 show another extraction tool 46 configured toextract an artificial disc 10 with two keels 30 on each on the upperbone attachment surface 26 and two keels on the lower attachment surface34 of the artificial disc 10. FIG. 27 shows a side view of theextraction tool 46. FIG. 28 shows a top view of the extraction tool 46.The extraction tool 46 functions as discussed above except as otherwisenoted. The upper member 50 and lower member 52 of the extraction tool 46are joined together at the proximal end of the extraction tool 46. Theupper arm 58 and a lower arm 58 extend distally from the body 54. A tine62 is disposed at the distal end of each of the upper arm 58 and lowerarm 58. The upper member 50 of the extraction tool and the lower member52 of the extraction tool are joined together at the proximal end of theextraction tool 46, allowing the upper member 50 and lower member 52 tobe inserted together between the respective upper bone attachmentsurface 26 and lower bone attachment surface 34 of an artificial disc 10and the adjacent vertebrae 38 at the same time. The upper tine 62 isinserted above the artificial disc 10 and the lower tine 62 is insertedbeneath the artificial disc 10 during use as shown in FIG. 14 .

Each tine 62 includes a thin tine body 98 with a tip 102. The tine body98 is made thin as it is driven between the installed artificial disc 10and the vertebra 38 during use. One outside face of the tip 102 of eachtine 62 is beveled and tapers such that the distal end of the tine body98 is thinner than the proximal tine body 98. The tine 62 is flat on theside which faces the artificial disc 10 and the tapered face of the tip102 is located on the side of the tine body 98 which faces away from theartificial disc 10 in use and contacts the vertebra 38. The tine 62 isshaped so that the flat inner side slides along the bone attachmentsurface 26, 34 of the artificial disc 10 and the tapered face of the tip102 slides along the prepared surface of the vertebra 38; minimizingdamage to the bone and wedging between the bone 38 and the artificialdisc 10 to dislodge the keels 30 from the bone. The tine body 98 issufficiently long to capture the artificial disc 10 in a space 112between tines 62 in the assembled extraction tool 46 as the extractiontool receives an artificial disc 10.

The proximal end of the extraction tool 46 includes shoulders 126 and arecess 130 located distally from the shoulders 126. A slap handle 118may be attached to the shoulders 126 and used to extract the artificialdisc 10 if desired. The distal end of the extraction tool may be roundedto allow it to me more easily driven between the artificial disc 10 anda vertebra 38.

The extraction tool is shown fully inserted around an installedartificial disc 10. The tines 62 extend along the anterior/posteriorlength of the artificial disc 10 and both the upper member 50 and thelower member 52 of the extraction tool 46 have been inserted to an equaldepth relative to the artificial disc 10. A clamp, collar 134, disposedaround the extraction tool body 54 may be used to clamp the tines 62against the artificial disc 10. The extraction tool body 54 tapers andbecomes larger towards the distal end such that the proximal end of theextraction tool body 54 is smaller and the distal end of the extractiontool body 54 is larger. Moving the collar 134 towards the distal end ofthe extraction tool 46 will cause the collar 134 to engage theextraction tool body 54 and press the upper member 50 and lower member52 of the extraction tool 46 against each other. This will secure theartificial disc 10 between the tines 62. The extraction tool body 54 andthe inside surface of the collar 134 may be smooth and the collar 134may be slid distally along the extraction tool body 54. Alternatively,the extraction tool body 54 and the interior of the collar 134 may bethreaded as shown previously and these engaging threads may be used toadvance the collar distally along the extraction tool body 54.

The net distance 112 between the tines 62 (e.g. the distance with theupper member 50 and lower member 52 of the extraction tool fullycompressed together) is slightly less than the thickness of theartificial disc 10 so that a small space 194 is left between the uppermember 50 and lower member 52 of the extraction tool 46. This space 194allows the collar 134 to press the tines 62 against the artificial disc10.

FIG. 28 shows a top view of the extraction tool 46 and the artificialdisc 10. In the example embodiment, the tines 62 do not have keel tabs106 and may simply slide between the keels 30. The tines 62 may be madewider than the spacing between the keels 30 and one or more slots may beformed in the tines 62 which each allow a keel 30 to enter into a slotas the tines 62 are inserted around the artificial disc 10. This mayallow a similarly designed extraction tool to function with anartificial disc 10 with a single keel 30 or with other numbers of keels30. In many instances, there is little resistance to removing theartificial disc 10 once the tines 62 have been inserted between the boneattachment surfaces 26, 34 and the vertebrae 38. In these situations,the artificial disc 10 may be removed with just the frictional gripbetween the tines 62 and the bone attachment surfaces 26, 34.

The extraction tool 46 may alternatively have small keel tabs 106 whichare spring loaded and extend from the tines 62 once the tines 62 areinserted past the keels. The tines 62 may also have longitudinal slots198 therethrough with increase their lateral flexibility and small keeltabs 106 as shown in FIG. 26 . The slots 198 create smaller fingers inthe tines 62 which flex inwardly during insertion and allow the keeltabs 106 to pass between the keels 30 and then spring back outwardlyonce the tine 62 is fully inserted along the artificial disc 10.

FIG. 29 shows a top view of the extraction tool 46 of FIGS. 23 through26 or of the extraction tool 46 of FIGS. 27 and 28 . This drawingillustrates how the extraction tool tines 62 may be modified to includea slot 202 which receives a keel 30, such as in the artificial disc 10which includes a single keel 30 on the upper bone attachment surface 26and the lower bone attachment surface 34. FIG. 30 similarly shows a topview of the extraction tool 46 of FIGS. 23 through 26 or of theextraction tool 46 of FIGS. 27 and 28 and illustrates how the (upper andlower) tines 62 may be modified to include keel tabs 106. The keel tabs106 engage the keel 30 once the extraction tool 46 is insertedcompletely relative to the artificial disc 10. The tines 62 may alsohave longitudinal slots 198 therethrough which increase the lateralflexibility and small keel tabs 106 as shown in FIG. 26 . The slots 198create smaller fingers in the tines 62 which flex inwardly duringinsertion and allow the keel tabs 106 to pass between the keels 30 andthen spring back outwardly once the tine 62 is fully inserted along theartificial disc 10.

FIG. 31 shows a side view of another extraction tool 46. The extractiontool 46 is as described above and functions in the above manner exceptas noted. An upper arm 58 and a lower arm 58 are attached to the body 54by a scissor mechanism 206. A tine 62 is disposed at the distal end ofeach of the upper arm 58 and lower arm 58. The scissor mechanism 206 ismovable via a central drive rod 210 to move the upper member 50 of theextraction tool 46 and the lower member 52 of the extraction tool 46farther apart or closer together. The drive rod 210 may be a threadedrod which interacts with a threaded hole in the proximal center link ofthe scissor mechanism 206. The scissor mechanism 206 may be used toadjust the spacing 112 between the tines 62 to accommodate differentthickness of artificial discs 10 and also to press the tines 62 againstthe artificial disc bone attachment surfaces 26, 34.

The upper tine 62 and lower tine 62 are inserted together between therespective upper bone attachment surface 26 and lower bone attachmentsurface 34 of an artificial disc 10 and the adjacent vertebrae 38 at thesame time. The upper tine 62 is inserted above the artificial disc 10and the lower tine 62 is inserted beneath the artificial disc 10 duringuse as shown in FIG. 14 . Each tine 62 includes a thin tine body 98 witha tip 102. The tine body 98 is made thin as it is driven between theinstalled artificial disc 10 and the vertebra 38 during use. One outsideface of the tip 102 of each tine 62 is beveled and tapers such that thedistal end of the tine body 98 is thinner than the proximal tine body98. The tine 62 is flat on the side which faces the artificial disc 10and the tapered face of the tip 102 is located on the side of the tinebody 98 which faces away from the artificial disc 10 in use and contactsthe vertebra 38. The tine 62 is shaped so that the flat inner sideslides along the bone attachment surface 26, 34 of the artificial disc10 and the tapered face of the tip 102 slides along the prepared surfaceof the vertebra 38; minimizing damage to the bone and wedging betweenthe bone 38 and the artificial disc 10 to dislodge the keels 30 from thebone. The tine body 98 is sufficiently long to capture the artificialdisc 10 in a space 112 between tines 62 in the assembled extraction tool46 as the extraction tool receives an artificial disc 10. The tines 62may typically be as shown and described with respect to FIGS. 23 through30 .

The proximal end of the extraction tool 46 includes shoulders 126 and arecess 130 located distally from the shoulders 126. A slap handle 118may be attached to the shoulders 126 and used to extract the artificialdisc 10 if desired. The distal end of the extraction tool may be roundedto allow it to me more easily driven between the artificial disc 10 anda vertebra 38.

FIG. 32 shows a detailed drawing of a tine 62 on an extraction tool 46.The tine 62 includes keel tabs 106 which may retract within a channel orpocket 214 in the tine 62. A spring 218 is disposed between the keeltabs 106 in the pocket 214. The spring 218 presses the keel tabs 106 outof the pocket 214 as shown. Shoulders formed in the ends of the pocket214 and on the ends of the keel tabs 106 keep the keel tabs retainedwithin the pocket 214. The keel tabs are beveled on their distal facesand are pushed inwardly into the pocket 214 as the tine 62 is pushedbetween two keels. Once the tine 62 is moved sufficiently past the keels30, the keel tabs 106 extend outwardly from the pocket 214 and engagethe keel 30 when the tine 62 is pulled proximally to extract theartificial disc 10. The spring loaded keel tabs 106 may also be used ona single keel design by having a slot through the center of the tine 62to receive the keel 30 between two portions of the tine 62, pockets 214formed on both sides of the slot, springs 218 in each pocket 214, andkeel tabs 106 which are biased inwardly to the slot by the springs.

Referring to all of the above extraction tools 46; artificial discs 10may commonly be between about 0.5 cm thick and about 1.5 cm thick,between about 1 cm long and about 4 cm long, and between about 1 cm wideand about 4 cm wide. These dimensions vary with the location of theartificial disc 10 in the spine and the size of the patient.Accordingly, the extraction tool 46 is dimensioned to receive such anartificial disc 10. Commonly, the extraction tool 46 is between about 10cm long and about 20 cm long. The extraction tool vertebral space 112(the space between the tines 62) is often between about 0.5 cm and 1.5cm and the tines 62 are often between about 1 cm and about 5 cm long toreceive the desired artificial disc 10. The tines 62 are often betweenabout 0.5 mm and 2 mm thick and between about 5 mm wide and about 20 mmwide. The tines 62 are wider than they are thick, and often have a widthwhich is about 5 times, about 10 times, or about 15 times theirthickness. Commonly, the tines 62 have a width which is between about 5times and about 15 times their thickness, or a width which is betweenabout 5 times and about 10 times their thickness. The tapered tip 102 ofthe tines 62 is often between about 0.5 cm and about 1.5 cm long and thedistal tip of the tines 62 is often between about 0.1 mm and about 0.5mm thick. The tines 62 are parallel to each other and generally planar.The tines 62 are disposed in parallel horizontal planes (relative to anupright extraction tool 46 or an upright artificial disc 10) with avertical space between the tines to receive an artificial disc 10. Theupper tine 62 has a lower surface which is an artificial disc engagingsurface that is placed adjacent the upper bone attachment surface of theartificial disc and grips the upper bone attachment surface to removethe artificial disc form a spine. The upper tine 62 has an upper surfacewhich is a vertebra releasing surface which releases or separates anupper vertebra from the artificial disc upper bone attachment surface.The lower tine 62 has an upper surface which is an artificial discengaging surface that is placed adjacent the lower bone attachmentsurface of the artificial disc and grips the lower attachment surface toremove the artificial disc from a spine. The lower tine 62 has a lowersurface which is a vertebra releasing surface which releases orseparates a lower vertebra from the artificial disc lower boneattachment surface. In use, the upper tine upper bone releasing surfaceseparates an artificial disc from an upper vertebra and the lower tinelower bone releasing surface separates the artificial disc from a lowervertebra. The upper tine lower artificial disc engaging surface gripsthe upper surface of the artificial disc and the lower tine upperartificial disc engaging surface grips the lower surface of theartificial disc and the extraction tool removes the artificial disc fromthe spine.

The extraction tool 46 separates the artificial disc 10 from thevertebrae 38 with minimal damage to the vertebral bone and minimaltrauma to the surrounding tissue and allows for easier removal of theartificial disc 10. This allows the prepared surface of the vertebra tobe reused for implanting an artificial disc 10 without further resectionin many instances, reducing surgical complications.

The above description of illustrated examples of the present invention,including what is described in the Abstract, is not intended to beexhaustive or to be limitation to the precise forms disclosed. Whilespecific examples of the invention are described herein for illustrativepurposes, various equivalent modifications are possible withoutdeparting from the broader scope of the present claims. Indeed, it isappreciated that specific example dimensions, materials, etc., areprovided for explanation purposes and that other values may also beemployed in other examples in accordance with the teachings of thepresent invention.

What is claimed is:
 1. A method for removing an installed artificialspinal disc from between vertebrae comprising: selecting an artificialdisc extraction tool comprising: a body; a first upper tine extendingdistally from the body; a first lower tine extending distally from thebody; inserting the first upper tine between an upper bone attachmentsurface of an artificial disc and an upper vertebra to separate theupper vertebra from the upper bone attachment surface; inserting thefirst lower tine between a lower bone attachment surface of theartificial disc and a lower vertebra to separate the lower vertebra fromthe lower bone attachment surface; gripping the artificial disc betweenthe first upper tine and the first lower tine; and removing theartificial disc from between the upper vertebra and the lower vertebrawith the artificial disc extraction tool.
 2. The method of claim 1,wherein the first upper tine is generally planar and the first lowertine is generally planar and generally parallel to the first upper tine.3. The method of claim 2, wherein a distal portion of an upper surfaceof the first upper tine tapers to a distal tip of reduced thickness, andwherein a distal portion of a lower surface of the first upper lowertapers to a distal tip of reduced thickness.
 4. The method of claim 1,wherein the artificial spinal disc extraction tool comprises: an uppermember comprising; a body having a proximal end and a distal end; afirst upper arm which is attached to the distal end of the body andwhich extends distally from the distal end of the body; wherein thefirst upper tine is attached to the distal end of the first upper armand extends distally from the first upper arm; a lower membercomprising; a body having a proximal end and a distal end; a first lowerarm which is attached to the distal end of the body and which extendsdistally from the distal end of the body; and wherein the first lowertine is attached to the distal end of the first lower arm and extendsdistally from the first lower arm; and wherein the method comprisesholding the upper member against the lower member to thereby grip theartificial disc between the first upper tine and the first lower tine.5. The method of claim 4, wherein the upper member and the lower memberare joined together near a proximal end of the extraction tool.
 6. Themethod of claim 4, wherein the upper member comprises: a second upperarm which is attached to the distal end of the body and which extendsdistally from the distal end of the body, and which is disposed adjacentthe first upper arm; a second upper tine which is attached to the distalend of the second upper arm and which extends distally from the secondupper arm adjacent the first upper tine; wherein the lower membercomprises: a second lower arm which is attached to the distal end of thebody and which extends distally from the distal end of the body, andwhich is disposed adjacent the first lower ann; a second lower tinewhich is attached to the distal end of the second lower arm and whichextends distally from the second lower arm adjacent the first lowertine; and wherein the method comprises: inserting the second upper tinebetween the upper bone attachment surface of an artificial disc and theupper vertebra to separate the vertebra from the upper bone attachmentsurface; inserting the second lower tine between the lower boneattachment surface of the artificial disc and the lower vertebra toseparate the vertebra from the lower bone attachment surface; and movingthe first upper tine and the second upper tine laterally to selectivelyincrease or decrease a distance therebetween and thereby selectivelygrip an artificial disc upper keel with the first upper tine and thesecond upper tine, and moving the first lower tine and second lower tinelaterally to selectively increase or decrease a distance therebetweenand thereby selectively grip an artificial disc lower keel with thefirst lower tine and the second lower tine.
 7. The method of claim 6,further comprising a first upper keel tab extending laterally from thefirst upper tine and a second upper keel tab extending laterally fromthe second upper tine, and wherein the first upper tine and first lowertine are movable laterally to engage the artificial disc upper keel bymoving the first upper keel tab and the second upper keel tab behind adistal end of the upper keel.
 8. The method of claim 1, wherein themethod comprises, after inserting the first upper tine between the upperbone attachment surface of the artificial disc and the upper vertebra,moving the first upper tine laterally against an artificial disc upperkeel to thereby engage the upper keel with first upper tine.
 9. Themethod of claim 1, wherein a distal end of the first upper tinecomprises a first upper keel tab which extends laterally from the distalend of the first upper tine, and wherein the method comprises, afterinserting the first upper tine between an upper bone attachment surfaceof the artificial disc and the upper vertebra, moving the first uppertine laterally towards an artificial disc upper keel to thereby positionthe first upper keel tab behind the first upper keel.
 10. A method forremoving an installed artificial spinal disc from between vertebraecomprising: selecting an artificial disc extraction tool comprising: abody; a first upper tine extending distally from the body; inserting thefirst upper tine between an upper bone attachment surface of anartificial disc and an upper vertebra to separate the upper vertebrafrom the upper bone attachment surface; and removing the artificial discfrom the upper vertebra with the artificial disc extraction tool. 11.The method of claim 10, wherein a distal end of the first upper tinecomprises a first upper keel tab which extends laterally from the distalend of the first upper tine, and wherein the method comprises, afterinserting the first upper tine between an upper bone attachment surfaceof the artificial disc and the upper vertebra, moving the first uppertine laterally towards an artificial disc upper keel to thereby positionthe first upper keel tab distally behind the first upper keel.
 12. Themethod of claim 10, wherein the artificial disc extraction toolcomprises: a first upper keel tab which extends laterally from a distalend of the first upper tine; and a second upper tine extending distallyfrom the body; and a second upper keel tab which extends laterally froma distal end of the second upper tine; and wherein the method comprises:inserting the second upper tine between the upper bone attachmentsurface of the artificial disc and the upper vertebra to separate theupper vertebra from the upper bone attachment surface; and moving thefirst upper tine and the second upper tine laterally to thereby positionthe first upper keel tab and the second upper keel tab distally behindan artificial disc upper keel.
 13. The method of claim 10, wherein theartificial disc extraction tool comprises: a first upper keel tab whichextends laterally from a distal end of the first upper tine; and asecond upper tine extending distally from the body; and a second upperkeel tab which extends laterally from a distal end of the second uppertine; and wherein the method comprises: inserting the second upper tinebetween the upper bone attachment surface of the artificial disc and theupper vertebra to separate the upper vertebra from the upper boneattachment surface; and moving the first upper tine laterally to therebyposition the first upper keel tab distally behind a first artificialdisc upper keel moving the second upper tine laterally to therebyposition the second upper keel tab distally behind a second artificialdisc upper keel.
 14. The method of claim 10, wherein the methodcomprises, after inserting the first upper tine between the upper boneattachment surface of the artificial disc and the upper vertebra, movingthe first upper tine laterally against an artificial disc upper keel tothereby engage the upper keel with first upper tine.
 15. The method ofclaim 10, wherein the artificial disc extraction tool comprises a secondupper tine extending distally from the body, and wherein the methodcomprises: inserting the second upper tine between the upper boneattachment surface of the artificial disc and the upper vertebra toseparate the upper vertebra from the upper bone attachment surface; andmoving the first upper tine laterally against an artificial disc upperkeel to thereby engage the upper keel with first upper tine.
 16. Themethod of claim 15, wherein the method comprises moving the first uppertine laterally towards the second upper tine to grip the artificial discupper keel between the first upper tine and the second upper tine. 17.The method of claim 15, wherein the method comprises moving the firstupper tine laterally away from the second upper tine to engage theartificial disc upper keel with the first upper tine and to engage asecond upper keel tab with the second upper tine.
 18. The method ofclaim 10, wherein the first upper tine is generally planar in shape. 19.The method of claim 18, wherein a distal portion of an upper surface ofthe first upper tine tapers to a distal tip of reduced thickness. 20.The method of claim 10, wherein the artificial disc extraction toolcomprises a first lower tine extending distally from the body, andwherein the method comprises: inserting the first lower tine between alower bone attachment surface of the artificial disc and a lowervertebra to separate the lower vertebra from the lower bone attachmentsurface; gripping the artificial disc between the first upper tine andthe first lower tine; and removing the artificial disc from between theupper vertebra and the lower vertebra with the artificial discextraction tool.
 21. The method of claim 20, wherein the first uppertine is generally planar in shape and the first lower tine is generallyplanar in shape and parallel to the first upper tine.